Using host traits to predict reservoir host species of rabies virus

Abstract

Wildlife are important reservoirs for many pathogens, yet the role that different species play in pathogen maintenance frequently remains unknown. This is the case for rabies, a viral disease of mammals. While Carnivora (carnivores) and Chiroptera (bats) are the canonical mammalian orders known to be responsible for the maintenance and onward transmission of rabies Lyssavirus (RABV), the role of most species within these orders remains unknown and is continually changing as a result of contemporary host shifting. We combined a trait-based analytical approach with gradient boosting machine learning models to identify physiological and ecological host features associated with being a reservoir for RABV. We then used a cooperative game theory approach to determine species-specific traits associated with known RABV reservoirs. Being a carnivore reservoir for RABV was associated with phylogenetic similarity to known RABV reservoirs, along with other traits such as having larger litters and earlier sexual maturity. For bats, location in the Americas and geographic range were the most important predictors of RABV reservoir status, along with having a large litter. Our models identified 44 carnivore and 34 bat species that are currently not recognized as RABV reservoirs, but that have trait profiles suggesting their capacity to be or become reservoirs. Further, our findings suggest that potential reservoir species among bats and carnivores occur both within and outside of areas with current RABV circulation. These results show the ability of a trait-based approach to detect potential reservoirs of infection and could inform rabies control programs and surveillance efforts by identifying the types of species and traits that facilitate RABV maintenance and transmission.

The science of the host–virus network

“…The approach is most valuable when the definitive reservoir is unknown 40 , additional reservoirs are suspected 41 or intermediate hosts are of interest 42 . Models can be easily tailored to these circumstances by using training data that reflect host competence (for example viral isolation instead of PCR or serology, or testing tick larvae for pathogens as a proxy of a host's ability to transmit 39 ) or distinguish reservoirs from incidental hosts 43 . These approaches have also been widely suggested as a way of triaging viral sampling in wildlife 41 , but model performance is variable, and this approach has only been tested in limited settings.…”

Rabies Virus Variants Detected from Cougar (Puma concolor) in Mexico 2000–2021

“…Although feline species such as the cougar have not been identified as rabies reservoirs, they could act as vectors and transmit the rabies virus to humans and other species [17]. Members of the Felidae family have the tendency of being solitary and have only one dietary category but have no other features than have been described as important to become a rabies virus reservoir species, such as phylogenetic similarity to known reservoirs, large litters (~3.5 young/litter) and early sexual maturity; these may be some reasons why no rabies reservoirs have been described for any feline species [18,19].…”

The Causes and Long-Term Consequences of Viral Encephalitis

“…The natural reservoirs of RABV are some wild carnivores, raccoons, and bat species. Remarkably, the dog is a domestic animal that serves as the main reservoir of this virus ( Burrell et al, 2017 ; Siepker et al, 2020 ; Worsley-Tonks et al, 2020 ).…”